Conventional air bag or bellows-type actuators for rail car brakes are typically mounted on the rail car truck bolster. The air bag-type actuators are in construction structurally similar to a bellows. They are formed of a flexible fabric material which expands axially under pressure supplied by the rail car reservoir to move the brake shoes into engagement with the wheels of the rail car. In the description which follows, the terms “air bag-type” and “bellows-type” are used interchangeably. The actuator is pressurized in response to release of air under pressure from the rail car reservoir to cause axial expansion of the actuator which, in turn, moves the brake lever to move the brake shoes into engagement with the wheels of the rail car. Conventionally, the air bag-type actuators are equipped with a pair of plates attached at their movable and fixed ends, termed “measuring plates”, which serve the purpose of providing a rail car inspector with relatively movable index marks for measuring the amount of travel of the actuator when the brakes are applied. This is done by the inspector using a tape measure placed against the measuring plates to measure the separation of the plates when the actuator has been inflated to the position in which the brakes are applied. This has proven to be an unduly time consuming procedure when a long string of rail cars needs to be checked, and in practice, the task is too often simply not done.